This space has resources often to help you create or find a venture or group. Often if you are creating one then business plays a part as you want to be able to be self-sufficient from the start or near there if you are funded.
One of the difficulties organisations have is looking at a business model to begin with. The first question being who do I sell services to if people who are in need want to use it and likley cannot afford.
This can be answered by partnering with a local organisations or services and selling your service to them. An example would be a day centre for vulnerable adults, the adults pay through their personal budgets to attend. Or a local authority pays for each person to attend sessions at a workshop your organisation provides as it finds it cheaper to use an external source rather than an internal one.
One thing to consider would be going to tender to get these services. Its where public services set out what service they need then your service shows if it ticks all the boxes and matches what the outcome of the service will be for the end user.
Organisations can also use membership or subscription to sustain itself depending on what you do in general. Like a business a organisation to be most effective must have a unique offering and benefit to the local and wider community. They can have a less unique purpose but there will be more competition for end users and funding. It may have greater challenges.
Check out the sources on building a organisation below: